[llvm-dev] LLVM Kaleidoscope : Compiling to Object Code - Segmentation Fault

[preejackie via llvm-dev]

Hi David

On 25/01/19 4:12 AM, David Blaikie wrote:
> Still haven't had much luck reproducing this
> On Thu, Jan 24, 2019 at 1:19 PM preejackie 
> <praveenvelliengiri at gmail.com <mailto:praveenvelliengiri at gmail.com>> 
> wrote:
>
>     Hi David!
>
>     Thanks for reaching out, the codegen part of the tutorial is fine,
>     but when I try to generate the object code file, it throws
>     segfault. Also please note that I'm using release build of llvm,
>     actually I don't know whether that is the root cause or not.
>
>     I also run through valgrind, it seems like a invalid read from stack.
>
>     |||Error Summary:
>     |
>
>     |1 errors in context 1 of 1:
>     ==4153== Invalid read of size 1
>     ==4153==    at 0x4AFEE0:
>     llvm::optional_detail::OptionalStorage<llvm::Reloc::Model,
>     true>::OptionalStorage(llvm::optional_detail::OptionalStorage<llvm::Reloc::Model,
>     true> const&) (in /home/preejackie/kld/toy)
>     ==4153==    by 0x4B098D:
>     llvm::RegisterTargetMachine<llvm::X86TargetMachine>::Allocator(llvm::Target
>     const&, llvm::Triple const&, llvm::StringRef, llvm::StringRef,
>     llvm::TargetOptions const&, llvm::Optional<llvm::Reloc::Model>,
>     llvm::Optional<llvm::CodeModel::Model>, llvm::CodeGenOpt::Level,
>     bool) (in /home/preejackie/kld/toy)
>     ==4153==    by 0x46CE5B: createTargetMachine (TargetRegistry.h:397)
>     ==4153==    by 0x46CE5B: main (kjit.cpp:1337)
>     ==4153==  Address 0x4 is not stack'd, malloc'd or (recently) free'd
>     |
>
>     Source compile command : clang++ -g -O3 kjit.cpp `llvm-config
>     --cxxflags --ldflags --system-libs --libs all` -o toy
>
>     Please, let me know that if you need some additional information :)
>
>     Thanks a lot
>
>
> Oh, hmm, this might be that ABI problem 
> https://bugs.llvm.org/show_bug.cgi?id=39427 - if the release you're 
> using was built with GCC and you're building your code with Clang, 
> that could be it.
>
> Maybe try building with GCC?
>
   Yes, I tried to compile with GCC it works fine.

   Thanks a lot

>     On 25/01/19 1:47 AM, David Blaikie wrote:
>>     Hi there!
>>
>>     Sorry to hear you're having trouble with the examples & thanks
>>     for reaching out.
>>
>>     I'm having some difficulty reproducing the failure mode you
>>     described. From the code sample, it sounds like you're in Chapter
>>     8 and I just took a look at Chapter 8 in my debug build and got
>>     this result:
>>
>>     $ ./bin/Kaleidoscope-Ch8
>>     ready> def average(x y) (x + y) * 0.5;
>>     Read function definition:
>>     define double @average(double %x, double %y) {
>>     entry:
>>       %y2 = alloca double
>>       %x1 = alloca double
>>       store double %x, double* %x1
>>       store double %y, double* %y2
>>       %x3 = load double, double* %x1
>>       %y4 = load double, double* %y2
>>       %addtmp = fadd double %x3, %y4
>>       %multmp = fmul double %addtmp, 5.000000e-01
>>       ret double %multmp
>>     }
>>
>>
>>     Any  ideas what you might be doing differently that I could do to
>>     try to reproduce the failure you're seeing?
>>
>>     On Thu, Jan 24, 2019 at 9:36 AM preejackie via llvm-dev
>>     <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote:
>>
>>         Hi all :)
>>
>>         I'm new to llvm!
>>
>>         I'm going through the kaleidoscope : compiling llvm IR to
>>         object code tutorial, code in the listings breaks and causes
>>         a segmentation fault. After some investigation through gdb,
>>         probably this constructor call, causing the segfault.
>>
>>         |Program received signal SIGSEGV, Segmentation fault.||
>>         ||0x00000000004afee0 in
>>         llvm::optional_detail::OptionalStorage<llvm::Reloc::Model,
>>         true>::OptionalStorage(llvm::optional_detail::OptionalStorage<llvm::Reloc::Model,
>>         true> const&) ()|
>>
>>         |Source code: |
>>
>>         TargetOptions opt;
>>         autoRM =Optional<Reloc::Model>();
>>         autoTheTargetMachine =
>>         Target->createTargetMachine(TargetTriple, CPU, Features, opt,
>>         RM);
>>
>>         Whether this behavior is already notified and is there any
>>         workaround available for it ? I would be great to know the
>>         root cause for this behavior.
>>
>>         Of course, the kaleidoscope is friendly and good introduction
>>         to llvm for beginners, thank you very much for developing :)
>>
>>         Thanks for your kind help
>>
>>         _______________________________________________
>>         LLVM Developers mailing list
>>         llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>
>>         https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
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